Environmentally benign synthesis of methyl 6-amino-5-cyano-4-aryl-2,4-dihydropyrano[2,3-c]pyrazole-3-carboxylates using CeO2 nanoparticles as a reusable and robust catalyst
A green and convenient approach for the synthesis of methyl 6-amino-5-cyano-4-aryl-2,4-dihydropyrano[2,3-c]pyrazole-3-carboxylates via a one-pot, multi-component reaction in water
A green and efficient one-pot, four-component synthesis of methyl 6-amino-5-cyano-4-aryl-2,4-dihydropyrano[2,3-c]pyrazole-3-carboxylates in water is described. The method is catalyst-free, atom-economical, and does not involve tedious work-up or purification affording the target compounds in good yields.
描述了一种绿色高效的一锅四组分甲基6-氨基-5-氰基-4-芳基-2,4-二氢吡喃并[2,3 - c ]吡唑-3-羧酸酯的合成方法。该方法是无催化剂的,原子经济的,并且不涉及繁琐的后处理或纯化,从而以良好的收率提供了目标化合物。
Uncapped SnO2 quantum dot catalyzed cascade assembling of four components: a rapid and green approach to the pyrano[2,3-c]pyrazole and spiro-2-oxindole derivatives
作者:Sanjay Paul、Koyel Pradhan、Sirshendu Ghosh、S.K. De、Asish R. Das
DOI:10.1016/j.tet.2014.02.077
日期:2014.9
A new uncapped SnO2 quantum dots (QDs) catalyzed strategy for the synthesis of substituted pyrano [2,3-c]pyrazole and spiro-2-oxindole derivatives has been developed via a multicomponent one pot approach in aqueous medium. The reactions can be performed at low catalyst loadings with excellent functional group tolerance. This communication also reports a comparative study of the efficiency related to the catalytic activity of uncapped SnO2 QDs, oleic acid capped SnO2 QDs, and SnO2 nanoflower. Uncapped SnO2 QDs, capped SnO2 QDs, and SnO2 nanoflower were prepared by simple solvothermal method and characterized by XRD, FESEM, and TEM images. The easy recovery of the catalyst and high yield of the products make the protocol attractive, sustainable, and economic. The catalyst was reused for six cycles with almost unaltered catalytic activity. (C) 2014 Elsevier Ltd. All rights reserved.